SingleColumnValueFilter should be able to find the column value even when it's
not specifically added as input on the scan.
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Key: HBASE-2198
URL: https://issues.apache.org/jira/browse/HBASE-2198
Project: Hadoop HBase
Issue Type: Improvement
Components: filters
Affects Versions: 0.20.3
Reporter: Ferdy
Whenever applying a SingleColumnValueFilter to a Scan that has specific columns
as it's input (but not the column to be checked in the Filter), the Filter
won't be able to find the value that it should be checking.
For example, let's say we want to do a scan, but we only need COLUMN_2 columns.
Furthermore, we only want rows that have a specific value for COLUMN_1. Using
the following code won't do the trick:
Scan scan = new Scan();
scan.addColumn(FAMILY, COLUMN_2);
SingleColumnValueFilter filter = new SingleColumnValueFilter(FAMILY, COLUMN_1,
CompareOp.EQUAL, TEST_VALUE);
filter.setFilterIfMissing(true);
scan.setFilter(filter);
However, we can make it work when specifically also adding the tested column as
an input column:
scan.addColumn(FAMILY, COLUMN_1);
Is this by design? Personally I think that adding a filter with columns tests
should not bother the user to check that it's also on the input. It is prone to
bugs.
I suggest either one of 3 solutions:
A) Update the Javadoc of Filter / SingleColumnValueFilter / possibly other
affecting Filters to indicate this behaviour.
B) Fix the problem client-side (i.e. prior to using a Scan object, it should
check that the corresponding inputs for filters are set, but only if the user
has configured specific input columns in the first place). This is perhaps
inefficient performance-wise, because unnecessary inputs columns are returned
to the user. (Inputs that would only have to be used for filtering).
C) Fix the problem server-side. This would me most efficient, because the input
column would only be read to do filtering at the regionserver.
What do you think?
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